No Warmth in Proximity
Our closest approach to the sun does make for the shortest season
Twilight Thursday and Friday evening reveals the new crescent moon low in the southwest with Venus blazing a few degrees away tight against the horizon. Venus sinks lower in the early evening sky over the next week, finally disappearing between the sun and earth on January 11. Then, after a few days absence, it reappears in pre-dawn skies, where it will blaze as the Morning Star until autumn.
Moonless skies provide a dark backdrop for this year’s Quadrantid meteor shower, which is at its best in the wee hours before dawn Friday and Saturday. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Boötes, but can appear anywhere in the sky. The Quadrantids can produce from 50 to 100 meteors an hour, but timing — or more aptly, luck — is essential, as this shower peaks within just a few hours, and then it’s over.
You shouldn’t have any trouble spotting Jupiter, which reaches opposition Sunday, when it will shine in our night skies from sunset until sunrise, far brighter than any star. At opposition, the gaseous giant is its closest to earth and farthest from the sun, with earth right between the two.
Mars rises around midnight and is high in the south as daybreak approaches. Far below the red planet is Saturn, actually a little brighter but harder to see so tight against the horizon.
Saturday, earth reaches its closest point to the sun for the year — called perihelion. At that point the sun is roughly 3 million miles closer to the sun than it is at aphelion in July. While 3 million miles may seem like a lot, the distance has little correlation with the change of seasons, which are a result of earth’s 231⁄2-degree tilted axis. It does, however, affect the length of the seasons, since when the earth is nearest the sun it is also traveling its fastest — more than three percent faster than at aphelion. As a result, the seasons come and go quicker this time of year, with the time between December’s solstice and March’s equinox almost five days shorter than from June’s solstice until September’s equinox. As a result, winter is the shortest season for those of us in the Northern Hemisphere.
Saturday, two weeks after solstice, is the latest sunrise of the year. Sunrise comes a few seconds earlier than the day before, and while the change will be subtle at first, by the end of the month the sun will rise more than 10 minutes earlier than it does now.